Comparison of lead and cerrobend blocks for incident photon Flux of 6 and 15 MV X-rays

During radiotherapy treatment, critical organs are shielded using lead and cerrobend blocks. The objective of this study is to compare the effects of lead and cerrobend shielding blocks on incident photon beam. Collimator scatter factors were measured for open square fields [3 x 3 cm to 40 x 40 cm] defined by collimator jaws and for fields blocked down to smaller asymmetric fields by using five different Lead and Cerrobend blocks for 6 and 15 MV photon beams from a Varian Clinac 2100C accelerator. The measurements in air were performed using Farmer type ionization chamber fitted with acrylic build up caps. The Block Tray Factor [BTF] increased with field size for both 6 and 15 MV photon beams. In case of Lead blocks, the extreme variations in BTF for 6 MV photon beam are 0.70%, 0.84%, 0.56%, 0.80% and 1.15%. Similarly, for 15 MV the maximum variations for Lead blocks are 0.46%, 0.60%, 0.83%, 0.88% and 1.10% respectively. No significant difference has been observed in the BTF of Cerrobend blocks for 6 and 15 MV photon beams. The dose received by a point in air apparently shielded by lead blocks has three main contributions: 1. Due to primary photon beam transmitted through the block, 2. Due to scattered photons, 3. Due to contamination electrons. These three factors collectively cause the increase in BTF with increasing field size, energy, and decreasing block size. The effect of shielding on the beam output increases with field size, beam energy and shield size. This increase follows almost the same pattern for both lead and cerrobend shielding blocks. Therefore shield factors for all field sizes, beam energies and shield sizes should be determined separately for precise patient dose delivery

[Comparison between the effect of dexamethasone luntophoresis and drug therapy on 60 cases with carpal tunnel syndrome]

Carpal tunnel syndrome [CTS] is the most common entrapment neuropathy in all peripheral nervous system e of it is one of the most important causes of disability in patients. This study was designed to compare the efficacy of luontophoresis and medical treatment for idiopathic CTS. 60 consecutive patients with CTS confirmed by electromyography participated randomly in two experimental groups [drug therapy], and luontophoresis. lntervention in each group include 20 daily treatment luontophoresis [4ma, positive electrode, 15 mm/session] applied to the area over the carpal tunnel of the wrist region. Measurement were performed before and after treatment and included pain assessment, electromyo and neurography measurement [motor and sensory latency, motor and sensory nerve conduction velocity], grip strength. Improvement was significantly more pronounced in Iuntophoresis group than drug therapy group for variables, motor latency [P<0/000], sensory latency [P< 0/005], hand grip [P<0/000], and pain relief [P<0/000]. In clinical findings atrophy was not observed. Nocturnal pain and paresthesia were reduced 80% in luntophoresis group but 46/6% in control group. Results indicate both luntophoresis and drugs were effective, but luntophoresis was better than drugs. Further investigation is needed to investigate the effects of combination of these treatments in patients with mild to sever CTS